47 lines
2.1 KiB
JavaScript
47 lines
2.1 KiB
JavaScript
"use strict";
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var _const = require("../const.js");
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class QuadraticUtils {
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/**
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* Calculate length of quadratic curve
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* @see {@link http://www.malczak.linuxpl.com/blog/quadratic-bezier-curve-length/}
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* for the detailed explanation of math behind this.
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* @private
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* @param fromX - x-coordinate of curve start point
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* @param fromY - y-coordinate of curve start point
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* @param cpX - x-coordinate of curve control point
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* @param cpY - y-coordinate of curve control point
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* @param toX - x-coordinate of curve end point
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* @param toY - y-coordinate of curve end point
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* @returns - Length of quadratic curve
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*/
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static curveLength(fromX, fromY, cpX, cpY, toX, toY) {
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const ax = fromX - 2 * cpX + toX, ay = fromY - 2 * cpY + toY, bx = 2 * cpX - 2 * fromX, by = 2 * cpY - 2 * fromY, a = 4 * (ax * ax + ay * ay), b = 4 * (ax * bx + ay * by), c = bx * bx + by * by, s = 2 * Math.sqrt(a + b + c), a2 = Math.sqrt(a), a32 = 2 * a * a2, c2 = 2 * Math.sqrt(c), ba = b / a2;
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return (a32 * s + a2 * b * (s - c2) + (4 * c * a - b * b) * Math.log((2 * a2 + ba + s) / (ba + c2))) / (4 * a32);
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}
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/**
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* Calculate the points for a quadratic bezier curve and then draws it.
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* Based on: https://stackoverflow.com/questions/785097/how-do-i-implement-a-bezier-curve-in-c
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* @private
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* @param cpX - Control point x
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* @param cpY - Control point y
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* @param toX - Destination point x
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* @param toY - Destination point y
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* @param points - Points to add segments to.
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*/
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static curveTo(cpX, cpY, toX, toY, points) {
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const fromX = points[points.length - 2], fromY = points[points.length - 1], n = _const.curves._segmentsCount(
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QuadraticUtils.curveLength(fromX, fromY, cpX, cpY, toX, toY)
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);
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let xa = 0, ya = 0;
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for (let i = 1; i <= n; ++i) {
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const j = i / n;
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xa = fromX + (cpX - fromX) * j, ya = fromY + (cpY - fromY) * j, points.push(
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xa + (cpX + (toX - cpX) * j - xa) * j,
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ya + (cpY + (toY - cpY) * j - ya) * j
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);
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}
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}
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}
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exports.QuadraticUtils = QuadraticUtils;
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//# sourceMappingURL=QuadraticUtils.js.map
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